53 454 patients 55 to 74 years of age (59% men) who had a cigarette smoking history of ≥ 30 pack-years and, if former smokers, had quit within the previous 15 years. Exclusion criteria included previous diagnosis of lung cancer, chest CT within 18 months, hemoptysis, and unexplained weight loss > 6.8 kg (15 lb) in the preceding year.

Adherence to screening was 95% and 93% in the CT and radiography groups, respectively. 24% and 6.9% of CT and radiography screening tests were classified as positive. Of positive tests, 96% and 95% were false positives in the CT and radiography groups. The main results are in the Table. 1.4% of patients in the CT group and 1.6% in the radiology group had ≥ 1 complication after diagnostic evaluation for a positive screening test result.